GB wrote:My understanding is that they do not work as well in the U.S.A. because of its 110 Volt AC electric power.

There is 220V available within twenty yards of where you sit reading this. I'd bet my two group on it.

We have 220V going to nearly every residence in the country, and most of the businesses. We just split it up at the panel and distribute most of it around the house as 110V.

In theory an HX machine (when brewing) is basically functioning as a thermobloc machine would... the HX aspect serves to preheat/warm the group up to operating temperature while the boiler serves to heat the cool, incoming water. Maybe an electric heater in the grouphead and a thermobloc heater would be a very valid replacement for the HX? Heater bands can be quite precise actually, which may be a really good way to set up a thermobloc (110 power is the downside to using electric heating coils/bands/etc).

For an example of where this technology is already used and perfected... Anyone really familiar with plastic injection moulding, think of the heater bands around the screw... those are PID controlled too (and really that is a truly ideal application of a PID (at least according to our controls guy from cincinnati milacron))! All that to say, this could be a great way to get into true temperature profiling. Just my two cents.

I guess one way to tackle this would be to calculate how much energy the machine should be capable to put out. If we are talking about a machine with 4 groups, 2 steam pipes and hot water outlet, the maximal thermal energy output is huge. To be capable of that, there either needs to be huge heating capacity or huge energy reservoir. With a prosumer machine demands are smaller.

My gut feeling is that metal would not be very good for storing thermal energy, unlike water. Am I right? But if it is not crucial, then thermoblock would be a one good option. And I agree that boilers are very oldschool and clumsy.

If I was to design an espresso machine, it would have a boiler similar to a HX machine, but instead of HX it would mix hot and cold water to produce what ever is needed. You would need a boiler for steam in any case.

Actually I don't think heat storing that is actually the issue, it is actually heat transfer... water has a very high specific heat, especially compared to metals... like 8 times higher on average compared to steel. Thus, the real challenge is getting the water warm to be ready to be delivered to the espresso (i.e. it takes a heck of a lot more energy to increase a unit of water one degree F than it does steel one degree F)... up till now it seemed easiest to just store hot water that way it can be heated slowly and it large quantity... but an efficient thermoblock could possibly heat the water quickly and thus reduce the need for the boiler. And this is the thermodynamic/fluid dynamic issue that I think is the real heart of the OP question.

Point being, its not storage its delivery capacity, and a boiler is not necessarily the only way to do that... there are many thermosystems which do a similar process without having needed to transfer electric energy to heat energy well before the delivery is actually needed, thus I think the question is quite reasonable and a fairly good idea to explore.

Induction heaters enclosing a ferrous thermoblock?

Non-pressurized PID'd kettle to bring brew water and steaming water to a stable temperature, say 185F, and then it goes through either the brew thermoblock or the steam thermoblock.

Pysd

The point I was trying to make is that in Australia domestic electric power is 240 Volts. Which means power outlets (called power points there) and lights are 240 Volt. Sunbeam in Australia has taken advantage of the high power available due to the higher voltage to make by many accounts a decent domestic thermoblock espresso machine. And there are commercial machines that use the same technology as show in an earlier post.

You are correct, 220 Volt is available at the breaker box in my house in the U.S.A. But typically is only distributed to devices like driers and ovens. Almost all other distribution is 110 V to power outlets and lights etc. Without having a special circuit wired to my kitchen I cannot power up the Sunbeam. Although it may not be a bad idea?

Cheers
Geoffrey

HB wrote:That proves nothing. I've seen plenty of highly photogenic pours that tasted anywhere from exceptional to average to awful.

A beautiful poured shot might not be everything but it is surely a good start.
I have had thermoblock machines in the past and none have been able to pour a shot that remotely resembled the one from the Sunbeam.

Keep in mind that this thread is just discussing if thermoblock machines could be used in a commercial setting.

By the way, I have only had one good commercial shot out of hundreds. The place is Catalina in Houston.
Commercial espresso is usually bad IMHO.

mariowar wrote:I have had thermoblock machines in the past and none have been able to pour that remotely resembled the one from the Sunbeam.

It didn't hurt that the video was made by Paul Bassett (2003 World Barista Champion and Sunbeam spokesperson).

this has been an interesting discussion that makes me want to tinker. Ever since i PID'd my first espresso machine, I've been trying to figure out a method for better temperature control. Conventional thinking is that stability = control. Chasing stability is still very worthwhile: current systems are starting to get close (or there, depending on your point of view) to true stability.

However, as the proponents of humped temperature profiles will tell you, temperature stability is only the ability to control the temperature in a crude manner. Stability is actually the enemy of true temperature profiling. The ability to control the temperature throughout the extraction pushes the boundaries and future of espresso. Perhaps a flat profile is best - but maybe for a particular coffee, or even a particular person. The ability to profile temperature enhances control - and more control is better (unless you want to factor in price, but let's stay theoretical, OK?)

So, I currently see two routes for temperature profiling - a low mass/precise heat solution (thermobloc falls into this category) or a mixing solution (mixing of hot and cold temperature boilers). There are advantages and disadvantages to each approach. Just to hit on a few: The low/mass precise heat approach is probably cheaper for a crude solution (perhaps a separate grouphead heater so you can trail the temp up or down through the shot) but more expensive for precision - precisely adding heat as the water flows through the thermobloc/grouphead is gonna be difficult. The mixing solution requires additional thermocouples and flowmeters for precision, but seems to have a fixed engineering solution that is achievable with todays technology. It's more expensive from the start, but easier to perfect.

All that is just my thoughts. I actually experimented a little with these concepts when i had my zaffiro working - i encased the E-61 in heater strips and ran a separate PID loop to keep the grouphead around 200. So i could start with my boiler water at 202 and my grouphead at 198, to tail the temperature up during the shot, or boiler at 198 and grouphead at 202 to tail the temp down. Ultimately, as i mention above, this approach (grouphead as thermobloc) is rather crude, and without great temperature stability in either the boiler or grouphead (probably +/- 1 degree each) and only the ability for simple rising or declining profiles, i never really got much out of it.

I think i'll have to get to work on a mixing solution.